FIG. 5 shows, as an example of a refrigerating apparatus, an indoor unit 21 of a typical wall-mounted air conditioner provided with a cross flow fan 29. In FIG. 5, the air conditioner 21 includes a casing main body 20. First and second air intake grills 23, 24 are formed in the upper surface and the upper portion of the front surface of the casing main body 20. An air outlet 25 is provided at the lower corner of the front surface of the casing main body 20.
Also, a flow duct 27, which extend from the air intake grills 23, 24 toward the air outlet 25, is provided in the casing main body 20. An indoor heat exchanger 26 having a lambdoid cross-section facing the first and second air intake grills 23, 24 is provided at the upstream section of the flow duct 27. A cross flow fan 29, a tongue 22, and a scroll portion 30 are sequentially installed adjacent to each other at the downstream section of the flow duct 27. The tongue 22 and the scroll portion 30 form a vortex fan housing, which has opening portions 30a, 22a. A vane wheel (fan rotor) 29a of the cross flow fan 29 is located in the opening portions 30a, 22a to rotate in the direction of the arrow (clockwise in FIG. 5).
The tongue 22 is arranged in the vicinity of the second air intake grill 24 along the outer diameter of the vane wheel (fan rotor) 29a of the cross flow fan 29, and has a predetermined height. The lower portion of the tongue 22 is connected to an air-flow guiding portion 22b, which also serves as a drain pan below the indoor heat exchanger 26. The downstream side of the air-flow guiding portion 22b and a downstream portion 30b of the scroll portion 30 form an air outlet path 28, which has a diffuser structure as shown in the drawing and extends toward the air outlet 25, such that the airflow blown out of the vane wheel 29a of the cross flow fan 29 is efficiently blown out from the air outlet 25.
An air direction changing plate 31 is provided in the air outlet path 28 between the scroll portion 30 and the air-flow guiding portion 22b of the tongue 22.
The tongue 22 is formed as shown in the drawing. As shown by the arrows in chain lines, the flow of air from the indoor heat exchanger 26 through the vane wheel 29 of the cross flow fan 29 to the air outlet 25 proceeds through the vane wheel 29a in a direction perpendicular to the rotary shaft of the vane wheel 29a and blown out from the vane wheel 29a while curving along the rotation direction as a whole, and is subsequently bent along the air outlet path 28 and blown out from the air outlet 25.
The wind speed distribution during low load operation in the indoor heat exchanger 26 for an air conditioner configured as described above was analyzed, dividing the indoor heat exchanger 26 into a section A, a section B, a section C, and a section D as shown in FIG. 5. The wind speed at the section D, which directly faces the second air intake grill 24, is the highest. The wind speed at the section C, which faces the first air intake grill 23 in an inclined state, is slightly reduced as compared to the section D. Also, at the section B, which is covered with the upper portion of the casing main body 20 and into which air does not directly flow, the wind speed is further reduced as compared to the section C. Furthermore, at the section A where air is blocked by the tongue 22, the wind speed is further reduced as compared to the section B.
The above-mentioned indoor heat exchanger 26 of the air conditioner provided with multiple paths generally has a flow divider 3 including flow dividing paths P1, P2 as shown in FIG. 6 in order to divide refrigerant that flows into the main body of the indoor heat exchanger 26 to the paths of the main body of the indoor heat exchanger 26. The flow divider 3 determines the refrigerant distribution ratio of the flow dividing paths P1, P2 in accordance with the rated operation. A refrigerant supply pipe 4 is provided at the inlet of the flow divider 3.
Therefore, during the rated operation, the refrigerant temperatures at the outlets of the paths of the indoor heat exchanger 26 are approximately equal (expressed by the thickness of the arrows in FIG. 6). However, during low load operation in which the refrigerant amount is reduced, that is, during partial load operation, the following problem arises due to the influence of the wind speed distribution of the indoor heat exchanger 26 that differs in accordance with the position in the flow duct as described above. That is, as shown in the graph of FIG. 7, since there is a margin in the heat exchange capacity at path P1, 8A of a part WF where the wind speed is high, the refrigerant temperature is high at the outlet of the paths. In contrast, as for refrigerant at paths P2, 8B of a part WS where the wind speed is low, since there is no margin in the heat exchange capacity, the refrigerant temperature at the outlet becomes lower than the refrigerant temperature at the outlet of the paths where the wind speed is high (see ΔT in FIG. 7). In the graph of FIG. 7, the paths P1, 8A of the part WF where the wind speed is high are shown in white, and the paths P2, 8B of the part WS where the wind speed is low is shown with dots.
As a method for solving such a problem, conventionally, the above-mentioned paths are each provided with a refrigerant flow regulating valve. The refrigerant temperature at the outlets of the paths are equalized by adjusting the refrigerant flow rate of the paths in accordance with the temperature detected by temperature detectors provided at the outlets of the paths (for example, refer to patent document 1).
[Patent Document 1] Japanese Laid-Open Patent Publication No. 5-118682